mir-php

A PHP static analysis engine written in Rust.

mir-php performs type inference and semantic diagnostics on PHP source code. It operates directly on php_ast AST slices with no dependency on any LSP framework, making it usable as a standalone linter, a CI tool, or an embedded library.

Features

Type inference — infers variable types from assignments ($x = new Foo(), $x = 42, typed parameters, etc.) and exposes them via TypeEnv
Undefined symbol detection — flags calls to undefined functions and classes
Arity checking — warns when too few or too many arguments are passed
Undefined variable detection — finds uses of variables never assigned in the current function scope
Return-type checking — warns when a literal return value is incompatible with the declared return type (e.g. return "hello" in an int function)
Null-safety — warns when a method is called directly on null
Built-in stubs — ~200 PHP core functions and ~60 built-in classes/interfaces are pre-loaded so standard-library calls are never flagged as undefined

Library usage

use bumpalo::Bump;

let arena = Bump::new();
let source = "<?php\nfunction add(int $a, int $b): int { return $a + $b; }\nadd(1);";
let program = php_rs_parser::parse(&arena, source).program;

// Semantic diagnostics
let diags = mir_php::analyze(source, &program.stmts, &[(source, &program.stmts)]);
for d in &diags {
    println!("{}:{} — {}", d.start_line + 1, d.start_char + 1, d.message);
}

// Type inference
let env = mir_php::infer(&program.stmts);
if let Some(cls) = env.class_name("$obj") {
    println!("$obj is a {cls}");
}

CLI usage

cargo install mir-php

# Human-readable output
mir-php src/Foo.php src/Bar.php

# JSON output (suitable for editor integrations)
mir-php --json src/**/*.php

Exit code is 0 when no issues are found, 1 when there are warnings or errors, and 2 for usage errors (bad arguments, unreadable files).

Integration with php-lsp

mir-php is the analysis backend for php-lsp. php-lsp parses documents into ParsedDoc values (owning their bumpalo arenas), then passes the raw AST slices into mir_php::analyze() and converts the results into LSP Diagnostic objects.

License